The objective of this K08 project is to test one of the two major current hypotheses about the role of glutamate in glaucomatous retinal ganglion cell (RGC) death. According to this hypothesis one result of elevated IOP is a derangement of the glutamate metabolic cycle in RGCs. This derangement results in glutamate excitotoxicity that has a primary role in the pathogenesis of glaucoma. Aim 1 and 2 of this project test the second component of this hypothesis; aim 3 tests the first component. Aim 1 is to determine the effects of a deranged glutamate metabolic cycle in the retina on the RGC function and survival. Antisense oligonucleotides to the glutamate metabolizing enzymes, glutamate dehydrogenase (GDH) and glutamine synthetase (GS) and to glutamate transporters (GLAST) will be used to inhibit glutamate metabolism and uptake in RGCs. Their effects will be determined in tissue culture and then following intra-vitreal administration rats to assess RGC survival, activities and amounts of GDH. GS and GLAST, intra-vitreal glutamate concentrations, and visual function by electroretinography. Aim 2 tests whether glutamate antagonists and anti-apoptosis agents can reverse the effects of a deranged glutamate cycle in the retina caused by the antisense oligonucleotides. Aim 3 is to determine whether changes in the glutamate metabolic cycle similar to those induced by the use of antisense oligonucleotides to GDH, GS and GLAST are present in a chronically elevated IOP model of glaucoma in rats. The K08 candidate has recently completed a clinical fellowship in the field of glaucoma and has begun a tenure track academic career in Mt. Sinai School of Medicine. While he does have some prior fundamental research experience, in order to embark upon the proposed studies he must first strengthen his skills in the areas of antisense design and pharmacokinetics and in some specific methods that will be used in testing the animals and assessing the outcomes. Mentoring will be provided by senior scientists, experts in these areas.